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carburetor Universal Joint binding

Posted: Tue Oct 28, 2025 6:54 am
by varmint
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Since I had to remove the choke rod in order to address the freeze plug issue...it's time to fix the carburetor universal joint binding that happens when ever I adjust the mixture while in cab. I can see that lower part of the universal joint is in a U shape but the choke rod part is in a V shape. The holes in the choke rod portion aren't even close to being parallel to each other.

Re: carburetor Universal Joint binding

Posted: Tue Oct 28, 2025 7:07 am
by Allan
Just bend them into parallel to make them engage on the other two bosses on the U joint cross piece. They have to be spread like that to get them over the cross, before bending the back into parallel.

Allan from down under.

Re: carburetor Universal Joint binding

Posted: Tue Oct 28, 2025 8:54 am
by Mike Silbert
The 1925-1927 Car swivel "U-Joint" is notorious for binding when turning.
There are some things that can be done to make it reasonable.
1) Most cars I see are missing the bushing up by the dash.
https://www.modeltford.com/item/4590.aspx
The bushing prevents the rod "pointer" from digging into the dash, it moves the rod up to make it easier to grab and turn, and it slows down a rattle.
It can also prevent the u-joint from binding by pulling it up closer to where it belongs.
And while you are at it make sure the bushing is in place on the firewall to minimum rattles.
https://www.modeltford.com/item/4594.aspx

2) The joint is cheap and often beyond ideal angle so make sure the sides are symmetrical and even with no burrs to catch on anything.
Paying attention while bending and making it nice ill pay off. Once it is done there will be no need to re-bend anything in the future, just slip the rod up the square drive.

3) The rods are universal and often need trimming since they can jam into the pivot, the hole might need to be redrilled also.

Re: carburetor Universal Joint binding

Posted: Tue Oct 28, 2025 9:05 am
by Adam
The reproduction top and bottom yoke parts are not made exactly right and require a bit of clearance-ing and fitting around the area of the universal joint. Look carefully at it when turning and you will see where you have to re-form and open up the top yoke to be a “u” and also grind some material away on the yoke ends and corners of the u-joint. I have fit a bunch of these over the last 25 years. The parts don’t work “right out of the box”.

Re: carburetor Universal Joint binding

Posted: Tue Oct 28, 2025 1:42 pm
by TXGOAT2
If you want a precise, slack free adjustment, substituting a length of brake line hose for the u joint could work. A 1/4 " drive, 1/4" swivel socket might be another choice.

Re: carburetor Universal Joint binding

Posted: Tue Oct 28, 2025 3:01 pm
by Norman Kling
There is also a longer rod for the closed cars, than for the open cars. Be sure you have the right length.
Norm

Re: carburetor Universal Joint binding

Posted: Tue Oct 28, 2025 8:49 pm
by varmint
Norm,
When I removed the rod completely from the carburetor, I could still feel binding, but I think I fixed it the right way.
Bending the two ears with their out-of-the-box length into a U shape looked like it may catch on the center shank. So, I used the Dremel again to mill out the center section, adding length to the ears, bent them into shape and painted it. I can no longer feel binding.
carburetor universal 03.jpg
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carburetor universal 04.jpg (45.82 KiB) Viewed 156 times

Re: carburetor Universal Joint binding

Posted: Fri Oct 31, 2025 12:38 pm
by Original Smith
I have a late '25 with that setup. All genuine Ford parts. Never had a problem.

Re: carburetor Universal Joint binding

Posted: Fri Oct 31, 2025 1:25 pm
by speedytinc
Original Smith wrote:
Fri Oct 31, 2025 12:38 pm
I have a late '25 with that setup. All genuine Ford parts. Never had a problem.
There it is.

The problem is these repop parts don't fit. You cant buy a part & expect it to fit correctly. T owners, or their hired mechanics need to have some skills.
As a carb rebuilder, my time is better spent repairing/restoring an original needle than making the repop part function.

Regarding 25-27 mixture parts:
1)The top nut doesn't thread down deep enough.
2)the needle friction tabs appear too long because the needle is too short.
3)The cast u-joint trunnions are 1/2 offset & too large in diameter.
All this stuff requires modification, especially if using with some original pieces.

That being said, we are fortunate to have these parts available. (to be modified)